Double acting jack



' April l, 1939. H. o. HAFERKQRN 2,153,888 v DOUBLE ACTING' JACK Filed Jan. 16, 1936 r l f4 i 52l I 1 2@ 15 g 15 flea fr' i6 s 35 35 x 2@ f 35 l Ik l" n I f I s la /0 1 y J 34 YW t l:

Patented Apr. 11, 1939 UNITED STATES ATENT OFFICE 2 Claims.

The invention relates to automobile jacks, and more particularly toa double screw jack especially adapted for engaging under a bumper or other outer portion of an automobile for raising one end thereof.

The modern automobile, with its low wheel suspension, balloon tires, and o-verhanging body, has created a demand for a so-called bumper jack adapted to raise one end of the automobile by engaging under a member of the bumper or other outer portion of the car.

Certain prior bumper jack constructions have utilized a single screw having a movable nut thereon acting as the lifting member, and the amount of lift required necessitates an excessively long screw, so that the jack is consequently awkward to handle and manipulate, and very difficult to store in the car when not in use.

In using these prior bumper jacks, the bumper or other member engaged by the jack is frequently at an angle, and tends to slide laterally in the lifting member when in raised position. When this occurs the upper part of the long screw is very apt to strike some portion of the car and damage the same.

I am aware that certain prior jacks have utilized a double screw construction, but those jacks are not designed nor adapted for engaging a bumper, and are not capable of producing the excessive amount of lift required. Moreover, in these prior double screw jacks, one screw raises at a time, making the lifting action very slow.

In most prior jack constructions a pinion and gear arrangement is used, requiring gear housings, and bearings or thrust washers, and since the gear ratio is limited by the size of serviceable gear teeth which'can be satisfactorily manufactured, the lifting action is always relatively slow and tedious.

These prior jack constructions have utilized cast malleable iron housings and nuts, and the drilling and tapping of malleable iron does not produce satisfactory or durable screw threads.

Accordingly, it is an object of the present invention to provide an improved double screw jack which is adapted to be used as a bumper jack.

Another object is to provide an improved double screw jack in which the lifting member is always positioned at the top of the jack.

Another object is to provide a double screw, double-acting bumper jack which will raise the load at an extremely rapid rate.

A further object is to provide a double screw bumper jack inwhich the housing and nut memworking parts, including the nut and housing member and screws, may be made of steel tubing.

And nally it is an object of the present invention to embody all of the foregoing advantageous features in an extremely simple and inexpensive construction, which is easy to handle and manipulate, and which requires a small amount of storage space.

These and other objects are attained by the improvements comprising the present invention, which may be stated in general terms as including two telescopic screws having opposite threads and a housing member having a nut at each end for simultaneously engaging each of the screws.

In the drawing forming part hereof Figure 1 is a longitudinal sectional View of the jack in collapsed position;

Fig. 2 is a longitudinal sectional View of the improved jack in extended position, and taken at 90 to the view of Fig. 1;

Fig. 3 is a transverse sectional view as on line 3 3, Fig. 1; and

Fig. 4 is a plan sectional View as on line 4 4, Fig. 2, distant parts not being shown.

Similar numerals refer to similar parts throughout the several views of the drawing.

The improved jack preferably includes a base plate Ill which may be a metal stamping, and has in its central portion a depression or socket II for supporting the bottom of a lower screw I2. The screw I2 is tubular and is provided with external preferably right hand threads I2a. Preferably the bottom of the screw I2 is welded to the base plate I0 as indicated at I3.

A tubular housing member Ii is provided, and

preferably has a nut member l5 secured on its of the housing I4 and is provided with internal v50 threads I8 which engage and screw on the external threads I9 of an upper tubular screw 20. The external threads I9 are preferably opposite handed to the external threads I2a of the lower screw, and in this case are left hand threads.

A load-engaging member 2! is secured to the upper end of screw 29, as by the pin 22, and is adapted for engaging a bumper bar or other member cf an automobile. Preferably, the member 2| is provided with stepped seating surfaces 24 and 25 for supporting different sizes of bumper bars indicated in dot-dash lines at B and B', and each seating surface slopes upwardly to an apex 24 or 25 in the center thereof. Thus the bumper bar is supported at the apex of one of the seats, and the sloping surfaces 24 or 25 allow for tilting or angling of the bar without causing the jack to tip over.

As shown, the upper screw 20 is of a size adapted to telescope within the lower screw I2 when the jack is collapsed. Holding means for preventing the upper screw from turning preferably includes an inverted U-shaped bar 26 slidable within the upper screw 20, and having sides 21 and top 28. The bar 25 is vertically slidably connected in the lower end of the upper screw 2U by means of pins 29 secured in the screw and extending a slight distance into the slot 3|] formed between the sides 2l of the U-shaped bar 25.

The lower end of the holding bar 26 is vertically slidable in the lower screw i2, and the sides of the bar are preferably formed with outturned and upturned feet 3l (Figs. 1 and 3) which are curved at their outer portions to slidably engage and conform to the inner surface of the lower screw I2,

A guide bar 33 is provided in the lower screw I2, and preferably has an angular foot 34 at its lower end which rests upon and is secured to the base plate Ill as by welding. The guide bar 33 is provided with a vertically extending slot 35, and a web member or key 35 is secured between the sides of the holding bar 25 at its lower end andA extends through the slot 35 for vertical sliding movement therein.

The holding member 26 slidably engaged in the slot 35 of the guide bar 33 provides an extensible member for preventing relative rotation of the screws or for preventing turning of the upper screw. Since the angular feet 3l always slidably engage the inner surface of the lower screw I2, the upper screw 20 is rigidly maintained in a Vertical position, so that any tilting force applied to the upper screw by the bumper bar is taken on the rigidly mounted lower screw instead of on the guide bar 33.

Means for rotating the tubular housing I4 to screw upwardly on the lower screw I2 and at the same time extend the upper screw 2D, preferably includes a ratchet mechanism indicated generally at 38, which may be made in two halves, secured together by bolts or rivets 38a.

The upper end of the tubular housing has an annular member 39 secured thereon and another annular member 40 is secured to the outside of member 39. In practice the nut IT and annular members 39 and 4U are all made of steel tubing and brazed to the tubular housing I4, in one 45. The inner end of the pin 41 is provided at one side with an angular portion 48 for ratcheting over the holes 42 when turned in the opposite direction, and a coil spring 49 acts between the housing and pin to yieldably urge the pin into the sockets 42. By grasping the flange portion 50 of the pin and pulling the same outwardly against the action of the spring 49, the pin may be turned through so as to engage the holes 42 for turning the housing I4 in the opposite direction.

When the handle 45 is turned to rotate the housing I4 for extending the jack, the housing I4 moves upwardly on screw I2 and simultaneously extends the upper screw 2U upwardly, until the load is raised to the desired point. Both screws are always controlled, that is, prevented from rotating, regardless of whether a load is being lifted or not.

When the housing I4 is rotated to collapse the jack, the key 36 slides downwardly in slot 33 and the pins 25 move downwardly in the slot 30 and at each side of the bar 33. The width of the bar 33 is therefore slightly less than the distance between the inner ends of pins 29, and the top of guide bar 33 is preferably tapered as shown at 52 to aid in guiding the inner ends of pins 29 downwardly along the edges of the bar 33.

When the jack is in collapsed position, the base plate I5, housing i4, and load-engaging member 2I form a closed grease compartment for the two screws, because the load-engaging member 2| closes the top screw 2U and the base plate I3 closes the lower screw I2. Accordingly, in closed position there is no possibility of any moisture or foreign material getting into the moving parts of the jack.

The tubular housing I4 and the nuts I5 and Il are constructed as a unit acting to operate both screws as the jack is extended and to enclose both screws when the jack is collapsed.

Practically all of the jack parts may be made of steel tubing so that no malleable castings are required, with the result that more durable and easier operating screw threads may be formed in the nuts I5 and Il.

The jack eliminates the use of pinions and gears and bearings of any sort, and yet operates with a minimum of friction because the only friction produced is between the nuts and screws.

Due t0 the fact that the jack is double-acting, that is, both screws act simultaneously, and due to the fact that the Whole tubular housing is turned by the ratchet mechanism, thus eliminating any gear ratios; the jack may be operated to raise a load at an extremely rapid rate.

The improved jack provides a lifting member which is always positioned at the top thereof, so that if the bumper bar slips out of the jack, there is no upwardly projecting member to strike and damage the car,

I claim:

1. A jack including a base plate, an upper tubular screw, a lower tubular screw secured to the base plate and adapted for telescoping over said upper screw, said screws having opposite handed external screw threads, a tubular member having nuts at its ends for engaging said screw threads, ratchet means carried on said tubular member for rotating the same, a holding member within the tubular member for preventing rotation of the upper screw, the upper end of said holding member having a non-rotatable vertical sliding connection with said upper screw, and the lower carried on said tubular housing for rotating the same, a guide bar secured to the base plate Within the lower screw, and a holding bar slidably non-rotatably connected at its upper end within said upper screw and slidably non-rotatably connected at its lower end with said guide bar, the lower end of said holding bar slidably engaging the inner surface of said lower screw.

HERBERT O. HAFERKORN. 

